When producing water resistant electronic devices units, sealing of microphones and loudspeakers of the electronic device must be made. Examples of such electronic devices are mobile phones, tablets, laptops and smart watches. Since the water resistant electronic device then becomes hermetically closed, the interior of the electronic device acts as an acoustical chamber. Although the sealing of the loudspeakers and the microphones, besides providing water resistance, also sonically seals the loudspeakers and the microphones from acoustical chamber, sound energy produced by the loudspeakers will find its way to the microphones through the acoustical chamber introducing so called raw echo. The raw echo may introduce problems with sound echo recorded by the microphones. An echo canceller may be used to cancel out such sound echo signal recorded by the microphone.
However, if a sealing of a microphone or loudspeaker is not fully functional, besides reduced water resistance, also an increase in the recording of raw echo by the microphone may be introduced. The increase in raw echo experienced by the microphone may be due a bad sealing of the loudspeaker leading to increased leakage of sound emitted by the loudspeaker into the electronic device acting as the acoustical chamber. Alternately or in combination, the increase in raw echo experienced by the microphone may be due a bad sealing of the microphone leading to increased leakage of raw echo out from the electronic device acting as the acoustical chamber to the microphone.
It is hard and expensive to examine an electronic device in order to find such bad sealing of a microphone and/or a loudspeaker. When performing an acoustical diagnosis of an electronic device by letting it play a sound stimuli from a loudspeaker to a microphone, the location and acoustic properties of the recording location is unknown. The acoustic properties of the environment the electronic device is located in very much influence how the sound stimulus is presented by the microphone. Is the electronic device in a small room that will amplify certain frequencies? Is it near a wall inducing sound reflections rendering the results more or less unusable? Hence, there is a need for a method for diagnosing if a loudspeaker or microphone sealing is not fully functional.